regulator: core: Add option to prevent disabling unused regulators

regulator: core: Add option to prevent disabling unused regulators

This may be useful for debugging and develompent purposes, when there are
drivers that depend on regulators to be enabled but do not request them.

It is inspired from the clk_ignore_unused and pd_ignore_unused parameters,
that are used to keep firmware-enabled clocks and power domains on even if
these are not used by drivers.

The parameter is not expected to be used in normal cases and should not be
needed on a platform with proper driver support.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Brian Masney <bmasney@redhat.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20231107190926.1185326-1-javierm@redhat.com
Signed-off-by: Mark Brown <broonie@kernel.org>